Chairgun can do all sorts of things. Another intended just for ranging work is Mero. it's available for all platforms and pretty easy to use. One obvious feature that may confuse is 2 scope magnifications. One is actual scope magnification where the calibration of the reticule is correct - the other is for the magnification the shooter wants to use. That can be the same or different.

Like always though the results need checking with real shooting.

BC's. I have heard that Chairguns method is not that precise and 2 spaced crono's is a better way. It seems Pyramid Air has a calculator on it's web site for that method. This is something I have not personally tried.

For BC's this page may be a good source. They use a radar unit that can actually track the pellets.
https://hardairmagazine.com/ballistic-coefficients/